Common White Grubs Of Northeast Ohio Nurseries
Compiled by
Betsy A. Anderson ([email protected]) Michael G. Klein ([email protected]) Michael E. Reding ([email protected]) James J. Moyseenko ([email protected])
The Horticultural Insects Laboratory USDA – ARS
1680 Madison Ave. Wooster, Ohio 44691
(330) 263-3897 http://www.oardc.ohio-state.edu/Atru/
Photos used with permission from Cornell University’s
New York State Agricultural Experiment Station (NYSAES).
Contents
White Grub Rastral Pattern Identification 1
European chafer, Rhizotrogus majalis 2
European chafer larva to adult sequence 3
Japanese beetle, Popillia japonica 4
Oriental beetle, Anomala orientalis 5
Asiatic garden beetle, Maladera castanea 6
Northern masked chafer, Cyclocephala borealis 7
Bumble flower beetle, Euphoria inda 8, 9
Rose chafer, Macrodactylus subspinosus 10
Comparison chart 11
White Grub (Scarab) Identification by Rastral Pattern
A hand lens can be used in the field to identify white grubs by looking at the arrangement of spines and hairs on the last abdominal segment (the raster). The Northern masked chafer and Bumble flower beetle have random hairs that do not form a pattern (see photos on pages 7 and 8). See page 9 for a drawing of the Rose chafer rastral pattern.
1
Location of raster on white grub
European chafer
Japanese beetle Oriental beetle
May-June beetle Asiatic garden beetle
(Photos: NYSAES.)
European chafer, Rhizotrogus majalis
2
13mm
Female Male
Male Female Female after with eggs expelling eggs
Eggs - young to mature
Mature grubs
Actively feeding Completed feeding
Pupae – young to mature
Prepupae
Photos: NYSAES
Rastral pattern on last abdominal segment
30mm
3
Japanese beetle, Popillia japonica
4
Adult
male foreleg female foreleg
Adult feeding damage on linden. Eggs young to mature
8-11 mm
Rastral pattern on last abdominal segment
14 mm
25mm
(Photos: NYSAES.)
Oriental beetle, Anomala (=Exomala) orientalis
5
Male Female
Color variations
9-10mm
Pupa
Prepupa Eggs
Rastral pattern
Asiatic garden beetle, Maladera castanea
The bulbous stipe on the maxilla is a characteristic that distinguishes the Asiatic garden beetle larva from other white grubs.
Bulbous stipe
Third instar grub
Stipe 19mm
Adult 8-11mm Pupa
Prepupa
(Photos:NYSAES.)
Rastral pattern
6
Northern Masked Chafer, Cyclocephala borealis
male female
Pupa
Young to mature eggs Third instar grub
Rastral pattern on last abdominal segment
16.8 mm
23mm
7
Bumble Flower Beetle, Euphoria inda L.
There is no real pattern to the hairs on the raster (the last abdominal segment).
Third instar larva
6 – 8 mm
10 – 14 mm
1.5 x 0.4 inches
pupa
prepupa
Adults emerging from pupal cells
(Photos: USDA /ARS, Horticultural Insects Lab, Wooster, OH)
male
raster
male female female
Adults have been seen flying in northeast Ohio at various times. Literature suggests Bumble
flower beetles mature in late summer and can be observed flying in the fall. They overwinter as adults and fly again in early spring. The adults are known to feed on flowers, ripe and rotting fruits such as grapes, apples and peaches and on sap from tree wounds and sunflower stalks. The larvae feed on decaying wood and plant material and are found in mulch, manure piles, and rotting vegetable waste. The larvae are distinctive in that they crawl on their backs like green June beetle larvae but differ by not having a defined raster pattern. The green June beetle has two parallel rows of hairs on the raster that resemble a zipper.
Grubs have been found in nursery containers in a couple of ways. Workers in this nursery tried to determine why some of the top-dressed pots were missing newly applied fertilizer. When the taxus on the left was lifted from the pot, grubs were found under the root ball, as seen below. Grub movement up and down in the pot apparently incorporated the fertilizer. Another way these grubs have been discovered in nursery containers has been by looking in the potting media of plants uprooted by skunks.
(Photos: USDA/ARS, Horticultural Insects Group, Wooster, OH)
Rose chafer, Macrodactylus subspinosus
Rose chafers are a serious pest of many plants including rose, grape, apple, cherry, strawberry, hydrangea, peony and many other ornamentals and vegetables. They feed on leaves, skeletonizing them much like Japanese beetles do, and severely damage flowers and fruits. The adults emerge in June and lay their eggs in grassy sandy areas. Upon hatching, the larvae feed on roots of grasses and overwinter as larvae.
12 mm
Adult Larva Larval rastral pattern
18mm
10
Comparison Table of Common White Grubs
Common Name
Scientific Name
Size of Adult (LxW)
Mature Grub
(inches)
Time of Adult
Activity
Adult Feeding
Oviposition
European chafer
Rhizotrogus majalis
0.6 x 0.3 in.
1.2 evening no light sandy loam
Japanese beetle
Popillia japonica
0.3-0.5 x 0.25 in.
1 day yes – nursery
prefer loam soils
Oriental beetle
Anomala orientalis
0.36-0.41 x 0.25 in.
0.98 day/evening no wide range of soils
Asiatic garden beetle
Maladera castanea
0.3-0.4 x 0.2 in.
0.75 night yes-garden
prefer loam soils
Northern masked chafer
Cyclocephala borealis
0.45 x 0.26 in.
1 night no prefer loam soils
Rose chafer
Macrodactylus subspinosa
0.4 in. (L)
0.71 day yes-flowers
sandy
June beetle
Phyllophaga spp.
0.3-2.5 x 0.15-1.25 in.
1-2.5 night yes-foliage
prefer loam soils
Bumble flower beetle
Euphoria inda 0.5-0.6 x 0.3-0.4 in.
2 day yes-fruit highly organic
11